65 



A REVISED CENSUS OF THE TASMANIAN 

 FLUVIATILE MOUAJSCA. 



By W. L. May. 



Plates IX. -XII. 



■ 1 12th July, L9 



On entering on a revision of the Tasmanian fresh- 

 water molluscs, the question naturally arises why should 

 this 1)" necessary, seeing the great amounl of attention 

 ■ given to this subject by a number of dis- 

 tinguished naturalists. The truth is that much i 

 lapping ha- occurred in previous work, creating many 

 , partly through ignorance, or uncertainty as 

 to what previously '1 species really they 



a, too nun h stress \\ as laid 

 on small variation in the erection of Bpecies, which varia- 

 tion prov 3 to be individual, and not specific. 



Tli $1 naturalists wh( una ap- 



'iicv and Gaimard, who in the Zoolog 

 tho Astrolabe. L835, describe and figure Paludina nigra 

 from I' : . aux Channel. Bourguegnat app ars 



ribing in Proc. Zool. Soc., 1854, our large 

 freshwal r limpei Ancylastrum. Reeve, in tin- Conch, 

 [con., b d Littorina paludinella, sube quently 



ibed by Tenison-Woods a- Ampullaria tasmanica* 

 and now placed in the genus Petterdiana. Sowerby 

 in the Conch. Icon, described seven species of Phyaa 

 ■ sent him by Legrand; several of these species 

 cannot be maintained. I!i~ P. vandiemenensis is a 



inly exotic, ii is a large, conspicuous form, that bas 

 nevei been taken again, ana was probably sent by Ronald 

 Gunn, who i- known to have made similar mistakes with 

 a number of marine sb IK Tin figure in Conch. Icon, 

 looks very lib of tin New '/.< aland forms. Von 



ens in ' - ribed Hydrobia tasmanica; this 



;s was not identified by local workers, and i 

 quently it. was twice i P.L.S N.S.W. 



for 1013 published a figure of Amnicola diemense Frauen- 

 feld, which appears to be the same a- Von Martens' 

 of //. tasmanica. Frauenfeld :ribed, in 



Hydrobia gunn i, another jpecies not recognised by local 

 u\(\ it h vera] t im< a ] ibed 11 ed 



ley op. cit. gives a figure from the probable type in the 



